Maryland Geological Survey 209 



Cell tubes polygonal ; their inner surface showing evidence of a few strong 

 longitudinal striiE. Septa frequent, from ten to fifteen in the space of 10 

 mm. ; thickness equal to that of the cell walls. Mural pores in one or two 

 ranges, comparatively large, circular, with margins distinctly elevated. 

 Cell walls thin, but frequently much thickened near the surface by silifi- 

 cation, and sometimes granulose or spinose on the inner face. On some 

 specimens the cells, at the surface, are nearly equal, having a diameter of 

 about 1.5 mm.; on other specimens the diameter varies from .66 mm. to 

 1.5 mm. On many specimens some of the cell tubes are larger and less 

 angular than those surrounding them, being a little more tlian 2 mm. in 

 diameter." Hall, 1887. 



A few specimens have been observed in the Coeymans of Maryland which 

 may be referred to this species, although their shape is not clearly shown to 

 be hemispherical, which is the chief distinction between the typical form 

 and the variety jyrcecedens. 



Occurrence. — Helderberg Formation, Coeymans Member. Dawson, 

 Maryland; Warren Point, Pennsylvania. New Scotland Member. 

 Devil's Backbone. 



Collection. — Maryland Geological Survey. 



Favosites heldeebergi^ var. PRiECEDENS Schuchert 



Plate XXII, Figs. 2-7 



Favosites helderdergiw var. praxedens Schuchert, 1903, Amer. Geol., vol. 

 xxxi, p. 164. 



Description. — Corallum very irregular in shape, varying from sub- 

 hemispherical to pyriform, clavate or almost digitate. Even the most 

 nearly hemispherical specimens have an undulating surface or lobate 

 protrusions. Consisting of numerous intimately united prismatic corallites 

 which diverge from jjoint of attachment. Epitheca not observed. 

 Corallites subequal in some specimens, in others rather unequal in diam- 

 eter. Walls thick. Tabulas close, varying in distance from -J diameter to 

 once diameter of tube. Mural pores in 1 to 3 rows, their edges raised, 

 diameter about 25 mm.; distance in specimen figured about .75 mm. 



Diameter of corallites 1 to 1.5 mm. In some small specimens referred 

 to this species corallites are less than 1 mm. diameter. 

 14 



